A door sash which is used for a window frame or the like of a door of an automobile is generally provided to be roll-formed into the shape shown in FIG. 8 from a plate material which is a single metal strip. A door sash 1 shown in FIG. 8 is configured of an overlapping section 2 in which plate materials are overlapped each other and welded to each other along a longitudinal direction, a tubular section 3 formed at one end portion of the overlapping section 2 and having a substantially D-shape when viewed in a cross section, flange sections 4 and 5 respectively formed to protrude from the other end portion of the overlapping section 2 to both sides, and a holder 6 which is provided on the side opposite to the tubular section 3 with respect to the overlapping section 2 and formed by curving an end portion of the plate material into a substantially semicircular shape.
Further, a glass channel (not shown) is fitted between the tubular section 3 and the flange section 4 protruding downward in FIG. 8, that is, toward a window glass W side. On the other hand, a weather strip 7 is fitted between the holder 6 and the flange section 5 protruding upward in FIG. 8, that is, toward a vehicle main body B side. When the weather strip 7 is fitted, a projection portion 5a of the flange section is fitted into a recess portion 7a of the weather strip 7 and the holder 6 is fitted into a recess portion 7b of the weather strip 7. PTL 1 discloses the same type of door sash.